Adaptive expression of host cell wall degrading enzymes in fungal disease: an example from Fusarium root rot of medicinal Coleus.

Quantity of extracellular proteins and activities two cell wall degrading enzymes pectinase and cellulase were determined in the culture filtrate of Fusarium solani, the causal organism of root rot of Coleus forskohlii. Substitution of carbon source in the medium with either pectin or carboxymethyl cellulose led to the increased production of extracellular proteins by the fungus. Pectinase and cellulase activity in the culture filtrate was detected only when the growth medium contained substituted carbon source in the form of pectin and CMC, respectively. Pectinase activity was highest after 5 days incubation and then decreased gradually with time but cellulase activity showed a steady time dependent increase. In vitro virulence study showed the requirement of both the enzymes for complete expression of rot symptoms on Coleus plants. Thus the present study established the adaptive, substrate dependent expression of the two enzymes by the fungus and also their involvement in the root rot disease of Coleus forskohlii.